During the past year, research has been pursued concerning (1) Etiological mechanisms underlying individual differences in alcohol consumption in rhesus monkeys, with an emphasis on paternal genetic contributions; (2) The relationship between social competence and serotonin in ferally living monkeys: To assess the generalizability of our laboratory findings, and to obtain a subject pool of inappropriately aggressive individuals with sufficient numbers to perform parametric analyses, we continued to investigate ferally-living adolescent male monkeys drawn from a subject pool of 4500 rhesus monkeys living on an island off the coast of South Carolina; (3) Developmental patterns of rhesus monkeys selectively bred for extremes in CSF 5-HIAA: A major part of the past year has involved the development of a selective breeding program to breed for extremes in CSF 5-HIAA concentration. Both the parents and the infants have been carefully assessed to investigate parental genetic contributions to excessive aggression and alcohol consumption; (4) Genetic differences in the serotonin system using molecular genetics techniques, including amplification of the serotonin 1A receptor gene in monkeys with increased and diminished CSF 5-HIAA, development of fibroblast cell lines to acquire DNA, and the development of techniques to type tryptophan hydroxylase; (5) Assessment of the pharmacokinetics of imipramine in monkeys showing excessive anxiety under both baseline and stressful conditions.